SN75ALS085

LAN ACCESS UNIT INTERFACE DUAL DRIVER/RECEIVER

SLLS054D – APRIL 1989 – REVISED OCTOBER 2001

2

POST OFFICE BOX 655303

description (continued)

The purpose of the loop functions is to provide a means by which system data-path verification can be done

to isolate faulty interfaces and assist in network diagnosis. The LOOP pins are TTL compatible and must be

held high for normal operation. When LOOP1 is taken low, the output of driver 1 (TXO1) immediately goes into

the idle state. Also, the input to receiver 1 is ignored, and a path from a transmit input (TXI1) to RXO1 is

established. When LOOP1 is taken back high, driver 1 and receiver 1 revert back to their normal operation.

When LOOP2 is taken low, a similar data path is established between TXI1 and RXO2. TXEN1 must be high

for the loop functions to operate, and TXEN1 can be used to gate the loop function if desired. During loop

operation, the respective RXEN reflects the status of TXEN1.

The SN75ALS085 is characterized for operation from 0

°C to 70°C.

AVAILABLE OPTIONS

PACKAGED DEVICES

TA

PLASTIC

SMALL OUTLINE

(DW)

PLASTIC DIP

(NT)

0

°C to 70°C

SN75ALS085DW

SN75ALS085NT

The DW package is available taped and reeled. Add the suffix R

to device type (e.g., SN75ALS085DWR).

Function Tables

RECEIVER (LOOP = H)

RXI

PREVIOUS

OUTPUTS

RXI

RXEN

RXEN

RXO

VID = 1315 mV to –175 mV,

tw < 25 ns

L

L

H

VID = –275 mV to –1315 mV

tw > 50 ns

X

H

L

VID = 318 mV to 1315 mV,

tw < 142 ns

H

H

H

VID = 318 mV to 1315 mV,

tw > 187 ns

X

L

H

H = high level, L = low level, X = don’t care

DRIVER (LOOP = H)

TXI

TXEN

PREVIOUS

TXO

OUTPUT

TXO

L

L

Idle

Idle

H

L

Idle

Idle

↓

H

Idle

L

L

H

Active

L

H < 260

µs

H

Active

H

H > 8

µs

H

Active

Idle

L

L > 8

µs

Active

Idle

H < 260 ns

L > 8

µs

Active

Idle

H < 260 ns

L < 260 ns

Active

H

H > 8

µs

L < 260 ns

Active

Idle

L

L < 260 ns

Active

L

H = VI ≥ VT max, L = VI ≤ VT min